Explosive Cartridge And A Method Of Arranging An Explosive Cartridge In A Blast Hole

ABSTRACT

An explosive cartridge for generating an explosion in a blast hole, the explosive cartridge comprising a flexible casing for containing an explosive and a mechanism for expanding the casing in a first direction and for simultaneously contracting the casing in a second direction which differs from the first direction.

This application claims the benefit of the filing date of EuropeanPatent Application No. 06020259.5 filed Sep. 27, 2006, the disclosure ofwhich is hereby incorporated herein by reference.

The invention relates to an explosive cartridge.

Beyond this, the invention relates to a method of arranging an explosivecartridge in a blast hole.

Furthermore, the invention relates to the use of an explosive cartridgefor material fragmentation, particularly for any type of rock, rockmass, concrete or comparable material fragmentation.

Explosive cartridges may be used in many technical fields for any typeof rock, rock mass, concrete or comparable material fragmentation.

U.S. Pat. No. 3,323,455 discloses a container for explosives for use inan expansible explosive cartridge having structurally weak rupturableportions formed by chemical action in situ on the container. These weakrupturable portions help to break the cartridge at predefined positionswhen tamped inside a borehole.

WO 2000/79212 discloses a method for setting and igniting a charge ofexplosives for geological investigations, comprising the followingsteps: a hole is drilled in the ground which is to be investigated; anexplosion chamber is hollowed out, whereby said explosion chamber has anexpanded form in relation to the bore hole at the end of said bore hole;an ignition element and an explosive container containing an explosivein a protective blister surrounding the ignition element are lowereddown into the explosion chamber; the explosive is pressed out of theexplosive container into the explosive chamber and the ignition elementis ignited. Thus, a pump and a small diameter hose are replaced throughwhich a borehole enlarged at the bottom could be completely filled aswell.

U.S. Pat. No. 3,696,703 discloses a water-proof package forwater-sensitive bulk-loaded blasting agents comprising an inner andouter plastic tube and mounted between them a liner folded up onto theinner tube in concertina fashion, said tubes being fitted with aconstriction to retain the liner within the tubes and with a cap toprotect the bottom end of the assembly, wherein the package isattachable to a loading hose for blasting agent and the liner is pushedout through the bottom end of the outer tube by the loading hose or theblasting agent, when charging commences.

U.S. Pat. No. 4,813,358 discloses an inflatable wand for positioningwithin an upward oriented, mining borehole and near a lower collaropening thereof wherein the wand provides a conduit for introducing andretaining liquid explosive materials within the borehole. The wandincludes a flexible tube with longitudinally oriented reinforcing fibersembedded in an elastic composition such as rubber. The tube isconstructed to permit radial elongation in response to a force arisingwithin the tube and directed radially outward, but to restrain againstaxial elongation during use. Such radial elongation arises because ofback pressure developed by the flowing explosive as it is impeded at avalve outlet at the distal end of the wand. Enlargement of the wandseals the opening of the borehole without destruction of the elasticmaterial on sharp points and edges of the borehole collar.

However, conventional explosive cartridges for any type of rock, rockmass, concrete or comparable material fragmentation do in many cases notallow to entirely fill up a blast hole formed in the ground. This wouldbe desired to obtain an efficient fragmentation result.

It is an object of the invention to enable to fill up the bottom of ablast hole with an explosive material in an efficient manner.

In order to achieve the object defined above, an explosive cartridge, amethod of arranging an explosive cartridge in a blast hole, and the useof an explosive cartridge for material fragmentation according to theindependent claims are provided.

According to an exemplary embodiment of the invention, an explosivecartridge for generating an explosion in a blast hole is provided, theexplosive cartridge comprising a flexible casing for containing anexplosive, and a mechanism for expanding the casing in a first directionand for simultaneously contracting the casing in a second directionwhich differs from the first direction.

According to another exemplary embodiment of the invention, a method ofarranging an explosive cartridge for generating an explosion in a blasthole is provided, the method comprising inserting the explosivecartridge in the blast hole, and expanding a casing of the explosivecartridge in a first direction and simultaneously contracting the casingin a second direction which differs from the first direction.

According to still another exemplary embodiment of the invention, anexplosive cartridge having the above mentioned features may be used inthe field of material fragmentation (particularly for any type of rock,rock mass, concrete or comparable material fragmentation).

The term “casing” may particularly denote the portion of the explosivecartridge which portion has a (for instance continuous) inner surfacesurrounding the explosive (such as a non-loose explosive sealed by asurrounding flexible casing) entirely. Thus, the casing may define asealed space accommodating explosive material, particularlyaccommodating explosive material of a fixed and defined amount.

According to an exemplary embodiment of the invention, an explosivecartridge (or a bullet) is provided for use in mining applications orthe like, wherein the explosive cartridge can be lowered in a previouslyformed blast hole and can be installed at the bottom of the borehole,that is to say in a deepest portion, of the blast hole. Due to thenecessity to lower the explosive cartridge, the lowest part of the blasthole is not entirely filled with the explosive cartridge in a lateraldirection directly after insertion. In contrast to this, a distancebetween the explosive cartridge and the walls delimiting the blast holeremains in many cases. To overcome such problems, according to anexemplary embodiment of the invention, a cartridge-internal mechanismmay be activated which expands an outer lower portion of the explosivecartridge so that the lower portion of the activated cartridge fills alarger or even the entire lateral space at the deepest portion of theblast hole. Simultaneously, an extension of the explosive cartridge inlowering (or length) direction is reduced by contracting the explosivecartridge when expanding the cartridge in the other direction, so thatthe density of explosive contained within the cartridge is not reducedby the lateral extension. This may make it possible to efficientlyinstall the explosive cartridge in a blast hole, and to enable anefficient force transmission in a subsequent detonation.

Thus, embodiments of the invention may make it possible that essentiallythe entire cross-section of a bore hole is filled with the cartridge.Therefore, material crushing in the deepest portion of the blast holeduring a detonation may be promoted.

Thus, even with a non-loose explosive charge, and therefore with a highexplosive density, an efficient blasting may be made possible.

By means of a contraction of the cartridge in a length direction, alateral expansion of the cartridge may be triggered in a controlledmanner. Therefore, it may be ensured that the cartridge fillsessentially the entire cross-section of the blast hole, particularly ina deepest portion of a blast hole, that is to say in a blind hole of theblast hole. This functionally combined length contraction and lateralexpansion of the cartridge may be performed before the actualdetonation, in other words when preparing or installing the cartridgefor an efficient subsequent detonation. By taking this measure, theavailable cross-section of the bore hole may be essentially completelybe used to be filled with the cartridge. This may improve the forcetransmission between explosive and surrounding rock material during thedetonation.

An explosive cartridge according to an exemplary embodiment of theinvention may be used in single or multiple hole and single or multiplerow blasting. For instance, in a rectangular drill hole pattern with acertain distance of the holes from the next free face (burden) and witha certain distance between the holes (side spacing) a number of blastholes may be drilled in the ground. A number of blast holes (forinstance one hundred) may then be filled with explosive cartridges.Using the cartridges, the ignition of the holes may be carried outsequentially and/or simultaneously. By providing a mechanism forexpanding the cartridge in the deepest portion of the blast hole withoutan undesired reduction of the density of explosive charge, particularlyby expanding the cartridge in a lateral direction and by contracting thecartridge in a longitudinal direction at the same time, the explosiveforce may be improved or optimized and the specific explosives energyinput into the blasted material may be increased.

Particularly, the functional coupling or combination of the radialexpansion and the longitudinal contraction may enable to obtain theseand other advantages.

An outer casing of the explosive cartridge may be manufactured of amechanically flexible material so as to allow the expansion andsimultaneous contraction to be carried out without being destroyed. Inthis context, the skilled person will understand that this purposerequires a certain flexibility which allows a sufficiently largeexpansion/contraction of at least a part of the casing without beingdamaged. The skilled person will further understand that this purposemay require a flexibility which is not too pronounced, so as to hold thecomponents contained within the casing without a significant deformationof the casing. For instance, polyethylene with a thickness of 0.5 mm maybe appropriate for these purposes. An alternative material for thecasing may be a rubber-type material.

The thickness of a material of the casing may vary in a verticaldirection, so that a high flexibility may be obtained in the deepestportion of the bore hole and a larger rigidity may be obtained at anupper portion of the cartridge in the bore hole. Additionally oralternatively, plastics or other materials having a varying, that is tosay spatially dependent rigidity, may be used. For example, apolyethylene foil may be used for the casing having a thickness of 1 mmin an upper portion of the cartridge, and 0.5 mm in the deepest portionof the cartridge.

Thus, a highly efficient expansion cartridge may be provided. Such anexpansion cartridge may comprise an explosive cartridge covered by aflexible plastic material. Triggered by a chemical reaction or bycompressed air or a mechanical mechanism, the length of the cartridgemay be reduced, and at the same time an expansion of the explosivecartridge in a radial direction may be carried out. Thus, an expansioncartridge according to an exemplary embodiment of the invention does notuse an isolated lateral swelling or expansion of the cartridge triggeredby a chemical reaction, which would result in a reduction of the densityof the explosive charge. In contrast to such a one-dimensional approach,embodiments of the invention combine such an expansion of the cartridgein a lateral direction with a contraction of the cartridge in a lengthdirection, thereby providing a two-dimensional solution for maintaininga high density of the explosive charge. Thus, a system for manufactureof an explosive charge with a reduced length and a simultaneousexpansion in a radial direction may be provided.

In the following, recognitions, investigations and considerations willbe presented based on which embodiments of the invention have beendeveloped.

For blasting in the field of surface mining and quarry, vertical orinclined blast holes may be drilled in the rock mass typically parallelto a wall to be broken. These blast holes can be subdrilled to a certainextent of for instance ⅓ of the burden (the burden may be the distancebetween the bore hole and the wall to be broken).

Due to the drilling procedure and due to a possible water flow from therock mass, the deepest portion of the blast hole is in many cases filledwith water and/or with muddy water.

Subsequently, loose explosive material or explosive material containedin a cartridge is inserted into such a bore or blast hole. Wheninserting a cartridge in the bore hole, it usually has a smallerdiameter than the blast hole. Consequently, the explosive cartridges donot entirely fill the blast hole in many cases. As a result, only a partof the blast hole volume can be effectively used for the blasting. Whenemploying cartridged emulsion explosive for blasting with a density ofclose to 1 g/cm³, this may also result in problems during loading.Namely, the cartridges may sink to the deepest portion of the blast holeonly in an insufficient or very slow manner. The density of muddy waterin the deepest portion of the blast hole is in many cases above 1 g/cm³.Thus, due to the small density difference between the explosivecartridges and the muddy water, only a very slow sinking of thecartridge to the deepest portion of the bore hole is obtained.

However, a properly fitting loading of the deepest portion of the blasthole and a reliable sinking of the explosive cartridges to the deepestportion of the blast hole is important for achieving a proper blastingresult with regard to a reliable breaking of the lowest portion of awall to be broken.

When employing gelatinous explosive with a slightly higher density forloading the deepest portion of the blast hole, the cartridges reliablysink to the deepest portion of the blast hole. However, in such asituation, the deepest portion of the blast hole is only insufficientlyused with regard to the blast hole cross-section.

Forming slits in the explosive cartridges does not solve this problementirely: When the cartridge to be lowered hits a water surface in theblast hole, a lateral expansion of the cartridge may occur, so that itwill be prevented that the entire bore hole cross section is filled bythe cartridge.

Each increase of the loading density (with regard to the density of theexplosive as well as to the degree of using the cross-section of thebore hole) results in an improved blasting quality and enables to selecta larger burden, that is to say a larger distance between the bore holeand the wall to be broken by the explosion. Particularly, increasing theburden has a large economical importance for blasting, since this mayresult in a significantly increased amount of rock per blast hole. Incombination with an increase of the burden, usually an increase of thelateral side distance between the blast holes occurs. Therefore, anincrease of the burden may in principle depend (for example with asquare function) from an increase of the drill pattern, and thus with alarger amount of rock per blast hole.

Apart from employing cartridged explosive for loading the deepestportion of the bore hole, it is also possible to use loose explosivewhich can be pumped via a tube into the deepest portion of the borehole. In such a configuration, an initiation charge (booster charge) isfirst inserted into the deepest portion of the bore hole with adetonator fixed thereto. This booster charge (for instance TNT, i.e.Trinitrotoluene, or PETN, i.e. Pentaerythritol Tetranitrate) is thenlowered along the ignition wires or the ignition tube to the deepestportion of the blast hole. Due to the high density of such initialexplosives, in many cases there is no problem that the booster sinksdirectly to the deepest portion of the blast hole. When subsequentlyloading loose explosive charge, the inserted explosive material may bemixed in a strong manner with the mud in the water in the deepestportion of the blast hole. This may result in the fact that between thepumped or inserted explosive and the booster charge in the deepestportion of the bore hole, only an insufficient contact is obtained. Thismay result in a non-successful ignition and/or to a bad initiation ofthe inserted main explosive.

A further circumstance which may be observed when pumping the explosivein the blast hole is the fact that strong currents of the water and theexplosive may be formed in the deepest portion of the bore hole. By suchdynamic streaming phenomena, the booster which has been previouslyinserted in the blast hole may be pressed out of the deepest portion ofthe blast hole when pumping the explosive in the blast hole. In somecases, the booster may buoy upwards several metres during the pumping.This upwardly buoying of booster charges inserted into the bore hole mayalso be the origin for many insufficient blast results, yielding a badfragmentation result in the lowest portion of the bottom of the wall tobe broken.

Summarizing, due to the presence of water in the deepest portion of theblast hole and due to the relatively high mud content in this water,problems with a correct loading of the deepest portion of the bore holemay occur.

Furthermore, when inserting cartridges or booster charges in aconventional manner, only a part of the cross-section of the blast holeis used for the loading. This may result in the effect that, with acertain blast hole diameter, only a small burden may be blasted, so thateffectiveness is lost compared to an entirely filled blast holecross-section.

In view of the above considerations, an exemplary embodiment of theinvention provides a system for manufacture of a bottom charge to bepositioned in a deepest portion of a blast hole. A correspondingcartridge may therefore fill essentially the entire cross-section of theblast hole.

According to an exemplary embodiment of the invention, a loading systemfor introducing an explosive charge in a bottom portion of a blast holemay include at least a part of the following components:

-   -   A cartridge comprising an explosive material (for instance an        emulsion explosive and/or a gelatinous explosive and/or a gel        explosive and/or a single component explosive, for instance        Nitropenta (Pentaerythritol Tetranitrate), TNT        (Trinitrotoluene), Hexogen (Cyclotrimethylene trinitramine),        etc.), preferably having a diameter of up to at the most        essentially ⅔ of a diameter of the blast hole and/or of a        density of larger than 1.4 g/cm³.    -   The length of the explosive cartridge may be more than 500 mm,        for example essentially 1000 mm.    -   An enclosure of the cartridge may comprise an unbreakable        elastic material, for instance made of a plastics.    -   A mechanism for reducing the length of the explosive cartridge        and for increasing the diameter of the explosive cartridge up to        the diameter of the blast hole. This can be achieved, for        instance, by means of a mechanically controlled pull or a push        system (for instance using a spring), by means of a chemically        activated system, by means of a vacuum (or low pressure)        controlled system and or by means of a pneumatically controlled        system.    -   A device for lowering the cartridge into the deepest portion of        a blast hole and for actuating the mechanism for reducing the        length and for increasing the diameter of the cartridge.

According to an exemplary embodiment, a bore hole charging system may beprovided comprising an explosive cartridge embedded in a flexibleplastic cover with a mechanism (for example provided with a chemicalreaction system or a compressed air system or a mechanical device) forreducing the length of the explosive cartridge while simultaneouslyexpanding the explosive cartridge in radial direction.

The expansion of the explosive cartridge to the diameter of the blasthole may be effected by a mechanical device or by a reaction initiatedby a chemical process or using compressed air.

The activation of the expansion mechanism after the insertion of thecartridge in the deepest portion of the blast hole may occur by amechanism to be activated from outside of or from an upper end of thebore hole (for instance using an igniter wire or a string, using atiming mechanism, by means of a delayed mechanical activation of acontraction spring, or by means of a delayed activated chemical reactionprocess). Beyond this, embodiments of the invention may also perform acontraction of the explosive cartridge in longitudinal direction by acompressed fluid (like air).

In a lower part of the explosive cartridge, a small hole may be providedin which an electrical, or a non-electrical or an electronic detonatormay be inserted.

After charging of one, two or more such expansion cartridges in thedeepest portion of a blast hole, a main mass of explosive charge may bedeposited onto this bottom charge.

Embodiments of the invention may allow to fill a bore hole in animproved manner, may allow to design the burden of the blast holes tothe limit of the surrounding rock and may further ensure that thedrilled bore hole volume is filled substantially entirely with explosivematerial. Thus, a ratio between a used portion of the bore hole and ofthe bore hole of almost 100% may be obtained. Embodiments of theinvention may contribute to design a drill pattern for blast work withan efficiency which may be increased by 20 to 30%, or more. Implementingembodiments of the invention may enable to increase the filling degreeof the blast holes when charging cartridged explosives fromapproximately 80% to essentially 100%.

According to an exemplary embodiment of the invention, the expansion ofthe cartridge may be achieved by a corresponding shortening of thelength of the cartridge, thereby engaging the walls of the bore hole bythe laterally expanded cartridge and by simultaneously maintaining ahigh density of the explosive material.

Next, further exemplary embodiments of the explosive cartridge will beexplained. However, these embodiments also apply for the method and forthe use.

The flexible casing may comprise a plastic, particularly polyethylene,or may comprise a rubber-type material. However, other plastic ornon-plastic materials may be used if such a material allows theexpansion in a radial and the compression in a longitudinal directionwithout being destroyed.

The flexible casing may comprise a flexible portion and a rigid portion.The flexible portion may be located adjacent to a bottom of the casingand may be adapted to be positioned in a deepest part of the blast hole.By taking this measure, it may be securely ensured that the deepestportion of the blast hole is really filled up essentially entirely withthe expanded cartridge, whereas an upper portion may be free of anexpansion or may experience a smaller expansion.

The flexible portion may have a smaller thickness than the rigidportion. By taking one and the same material for the flexible portionand for the rigid portion and by designing the rigid portion from athicker material (for instance 1 mm) as compared to the flexible portion(for instance 0.5 mm), the different elastic properties may be obtainedwith low effort.

Additionally or alternatively, the flexible portion may be made of amaterial being more flexible than a material of which the rigid portionis made. Thus, by selecting the material properties of the rigid portionand of the flexible portion, the elasticity requirements may be met.

In this context, the term “flexible” may particularly denote a portionof the casing having a value of the modules of elasticity which issmaller than a value of the modules of elasticity of a “rigid” portionof the casing.

The mechanism may be adapted in such a manner that the first directionis essentially perpendicular to the second direction. In other words, alateral expansion may be functionally combined with a longitudinalcompression, the longitudinal axis being perpendicular to the lateraldirection.

The mechanism may comprise at least one of the group consisting of amechanical pull mechanism, a mechanical push mechanism, a springmechanism, a pneumatically activatable mechanism, a chemicallyactivatable mechanism, a magnetically activatable mechanism, and anelectrically activatable mechanism. Mechanical, spring-based, pneumaticand chemically activatable embodiments are illustrated in the figuresexplained below. A magnetically activatable mechanism may comprise, forinstance, a permanent magnet and an electromagnet, wherein activation ofthe electromagnet by applying an appropriate current may generate amagnetic force which generates a repulsive force acting on the permanentmagnet, forcing the permanent magnet to be moved in a downwarddirection. Thus, the contraction in a longitudinal direction may beinitiated by such a magnetic trigger. Alternatively, electric forces maybe used to initiate the longitudinal compression, for instance using acapacitor. The plates of the capacitor may be charged with electriccharges of the same polarity, thereby forcing a lower capacitor plate togo downward under the influence of an electric force, resulting in acompression in the longitudinal direction.

The combined contraction-expansion mechanism may be activated from aremote position. In other words, a human operator standing outside ofthe bore hole may operate the mechanism of the explosive cartridge evenin an operation state in which the explosive cartridge is inserted intoa blast hole. This may allow to trigger the mechanism in a wired orwireless manner. A wired triggering may include the transmission of acontrol signal via a wire, or a direct activation energy. A wirelesstransmission may include the transmission of electromagnetic waves as atrigger signal for initiating the activation. Thus, the term “remotely”may particularly denote the fact that the mechanism can be activated bya user being positioned far away from the cartridge, since the mechanismdoes not make it necessary for the user to directly touch or contact thecartridge.

The mechanism may be activatable by a priming wire (an ignition wire), astring, a time switch, a delayed chemical reaction, and a delayed springmechanism. Also a remote control may be used to trigger the activationfrom a remote position.

A lowering unit may be provided and may be adapted for lowering theexplosive cartridge into the blast hole. This may be performed usingstrings or the like.

An explosive material may be contained in the casing. For instance, TNTor any other explosive material which may cause a detonation may becontained in the casing. An explosive charge accommodated in thecartridge may also comprises one of or a mixture of nitroglycerol, guncotton, ammonium nitrate, cellulose and barium sulphate.

The explosive cartridge may have a density of more than 1 g/cm³,particularly of at least 1.5 g/cm³, more particularly of at least 2g/cm³. With such density values, it may be ensured that the explosivecartridge sinks in water (having a density of 1 g/cm³), or even in muddywater which usually have a density of less than 1.5 g/cm³. Moregenerally, the average density of the explosive cartridge may be largerthan the density of the surrounding material (usually water and/or muddywater). This may ensure that the explosive cartridge securely sinks tothe deepest portion of a blast hole without any external activity. Whenthe explosive cartridge has a density of more than 1.5 g/cm³, it may beguaranteed that the cartridge reliably sinks to a deepest portion of theblast hole, even when the blast hole is at least partially filled withwater and/or muddy water.

A bottom portion of the explosive cartridge may comprise a small hole(for instance having a size of 6.9 mm) in which a detonator is inserted.This may allow to start the ignition and the blasting at the lowestportion of the blast hole which allows for an efficient detonation.

The aspects defined above and further aspects of the invention areapparent from the examples of embodiment to be described hereinafter andare explained with reference to these examples of embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter withreference to examples of embodiment but to which the invention is notlimited.

FIG. 1 to FIG. 4 illustrate explosive cartridges according to exemplaryembodiments of the invention.

DESCRIPTION OF EMBODIMENTS

The illustration in the drawing is schematically. In different drawings,similar or identical elements are provided with the same referencesigns.

In the following, referring to FIG. 1, an explosive cartridge 100according to an exemplary embodiment of the invention will be explained.

The explosive cartridge 100 is adapted for initiating, contributing orgenerating an explosion in a blast hole 101, that is to say in a holeextending along an essential longitudinal (for example vertical)direction 102 in a surrounding rock 103 which is indicated schematicallyin FIG. 1.

The explosive cartridge 100 comprises a flexible casing 104 containingan explosive indicated schematically with reference numeral 105. Theflexible casing 104 comprises a plastic foil made of polyethylene.

Furthermore, a mechanism for expanding the casing 104 in a firstdirection 106 and for simultaneously contracting the casing 104 in asecond direction 107 which is oriented essentially perpendicular to thefirst direction 106 is provided. The mechanism described is activatablefrom a remote position, that is to say from a position outside of theblast hole 101.

A bottom portion of the explosive cartridge 100 comprises a small holein which a detonator 108 is inserted.

According to the embodiment shown in FIG. 1, the activation of themechanism is performed using a compressed air tube.

As can be taken from FIG. 1, a fixation 109 is shown which allows to fixa compressed air tube which is directed towards the blast hole opening.By taking this measure, an air pressure of 3 bar to 5 bar may begenerated.

Furthermore, a chamber 110 is provided into which the compressed air isinjected and which forces an injection cartridge 111 to move in adownward direction 107. Reference numeral 111 denotes a double walledinjection cartridge which is pressed inside of an expansion cartridge112. A sliding direction of the injection cartridge 111 is indicated bythe reference numeral 107.

Furthermore, a thread guide or a groove guide is indicated withreference numeral 113.

The expansion cartridge 112 is filled with a plastified explosive and issurrounded with a resilient, soft or elastic foil 104.

As indicated in FIG. 1, a diameter of the explosive cartridge 100, d,may be in the order of magnitude of 80 mm, whereas a bore hole diameter,D, may be in the order of magnitude of 100 mm.

In the following, referring to FIG. 2, an explosive cartridge 200according to another exemplary embodiment of the invention will beexplained.

The explosive cartridge 200 differs from the explosive cartridge 100essentially in that, according to FIG. 2, the activation is initiatedvia a chemical reaction. For this purpose, a fixation 201 for a stringfor pulling out a cap after expanding the explosive cartridge 200 isprovided. Furthermore, a chamber 202 is provided which is filled withtwo or more (solid, liquid or gaseous) components which generate a gaslike carbon dioxide (CO₂) by a chemical reaction, and move the injectioncartridge 111 in a downward direction due to the pressure of thegenerated gas.

In the following, referring to FIG. 3, an explosive cartridge 300according to another exemplary embodiment of the invention will beexplained.

The embodiment of FIG. 3 differs from the embodiment in FIG. 1essentially with regard to the fact that, according to FIG. 3, theactivation is initiated using a mechanical rod.

For this purpose, a fixation 301 for a mechanical member is providedwhich is guided to an outer bore hole opening and by means of which theinjection cartridge 111 may be turned into the expansion cartridge 105.

Next, referring to FIG. 4, an explosive cartridge 400 according toanother exemplary embodiment of the invention will be explained.

The embodiment of FIG. 4 differs from the embodiment of FIG. 1essentially in that the activation is performed using a (biased) spring401. Furthermore, a fixation 402 is provided for fixing two or morestrings, one for lowering the explosive cartridge 400 and one foractivating the spring 401.

It should be noted that the term “comprising” does not exclude otherelements or features and the “a” or “an” does not exclude a plurality.Also elements described in association with different embodiments may becombined.

It should also be noted that reference signs in the claims shall not beconstrued as limiting the scope of the claims.

1. An explosive cartridge for generating an explosion in a blast hole,the explosive cartridge comprising: an at least partially flexiblecasing for containing an explosive; a mechanism for expanding the casingin a first direction and for simultaneously contracting the casing in asecond direction which differs from the first direction; and aninjection cartridge member and an expansion cartridge member, themechanism being activatable by inserting the injection cartridge memberinto the expansion cartridge member.
 2. The explosive cartridgeaccording to claim 1, wherein the flexible casing comprises at least oneof the group consisting of a plastic, polyethylene, and a rubber-typematerial.
 3. The explosive cartridge according to claim 1, wherein theflexible casing comprises a flexible portion and a rigid portion, theflexible portion being arranged adjacent to a bottom of the casing to bepositioned in a deepest part of the blast hole.
 4. The explosivecartridge according to claim 3, wherein the flexible portion of theflexible casing has a smaller thickness than the rigid portion of theflexible casing.
 5. The explosive cartridge according to claim 3,wherein the flexible portion of the flexible casing is made of a firstmaterial being more flexible than a second material of which the rigidportion is made, the first material being different from the secondmaterial.
 6. The explosive cartridge according to claim 1, wherein themechanism is adapted in such a manner that the first direction isessentially perpendicular to the second direction.
 7. The explosivecartridge according to claim 1, wherein the mechanism comprises at leastone of the group consisting of a mechanical pull mechanism, a mechanicalpush mechanism, a spring mechanism, a pneumatic mechanism, a chemicallyactivatable mechanism, a magnetic mechanism, and an electric mechanism.8. The explosive cartridge according to claim 1, wherein the mechanismis activatable remotely.
 9. The explosive cartridge according to claim1, wherein the mechanism is activatable by at least one of the groupconsisting of an ignition wire, a string, a time switch, a delayedchemical reaction, and a delayed spring mechanism.
 10. The explosivecartridge according to claim 1, comprising a lowering unit adapted forlowering the explosive cartridge into the blast hole.
 11. The explosivecartridge according to claim 1, comprising the explosive materialcontained in the casing, particularly comprising non-loose explosivematerial contained in the casing in a sealed manner.
 12. The explosivecartridge according to claim 1, having an average density of more than 1g/cm³, particularly of at least 1.4 g/cm³.
 13. The explosive cartridgeaccording to claim 1, wherein a bottom portion of the explosivecartridge comprises a hole in which a detonator is inserted.
 14. Theexplosive cartridge according to claim 1, wherein the mechanism is atleast partially integrated in the casing.
 15. (canceled)
 16. Theexplosive cartridge according to claim 1, wherein the at least partiallyflexible casing defines a sealed space accommodating a fixed amount ofthe explosive.
 17. A method of installing an explosive cartridge forgenerating an explosion in a blast hole, the method comprising:inserting the explosive cartridge in the blast hole; expanding a casingof the explosive cartridge in a first direction and simultaneouslycontracting the casing in a second direction which differs from thefirst direction; and providing an injection cartridge member and anexpansion cartridge member, the mechanism being activatable by insertingthe injection cartridge member into the expansion cartridge member. 18.The method according to claim 17, comprising performing the expandingand the contracting before generating an explosion in the blast hole.19. The method according to claim 17, comprising expanding the casing ina direction perpendicular to an extension of the blast hole andsimultaneously contracting the casing in a direction parallel to theextension of the blast hole.
 20. A method of using an explosivecartridge according to claim 1 in the field of material fragmentation.